The evaporation of a lysozyme solution drop containing Ca2+ ions on a superhydrophobic poly(methyl methacrylate) surface was probed by X-ray microbeam raster-diffraction. We observe the rapid deposition of fibrillar lysozyme with cross-b amyloidic structure at the interface of the drop with the substrate under conditions of weak acidity, close to physiological. The flows generated inside evaporating drops on superhydrophobic surfaces with very low adhesion forces can also be used for manipulating of matter at interfaces. Indeed, fibrillar lysozyme observed at the interface of the drop-residue to the substrate has been related to a local convective flow field developed during pinning of the drying drop. Aggregation into a fibrillar morphology with cross-b amyloidic structure has been observed by X-ray microdiffraction for small, natural peptides at the rim of drop-residues. These observations suggest that convective flow fields could be systematically explored for manipulating and probing of biopolymers such as proteins at interfaces. As an example we report here on the evaporation of drops of lysozyme solution, an approximately 14.7 kDa, 130 residue globular protein which is involved in egg shell formation. Flow-related shear-stress in blood vessels could well contribute to amyloid-associated diseases as suggested by b-peptide aggregation in microfluidic channels.
Related IIT publications
- A. Accardo, M. Burghammer, E. Di Cola, M. Reynolds, E. Di Fabrizio, C. Riekel, “Lysozyme fibrillation induced by convective flow under quasi contact-free conditions”, Soft Matter, 7, 6792-6796. DOI: 10.1039/c1sm05783a (2011).
- A. Accardo, M. Burghammer, E. Di Cola, M. Reynolds, E. Di Fabrizio, C. Riekel, “Calcium Carbonate Mineralization: X-ray Microdiffraction Probing of the Interface of an Evaporating Drop on a Superhydrophobic Surface”, Langmuir, 27(13), 8216-22. DOI.org/10.1021/la2014336 (2011).
- A. Accardo et al., “In Situ X-ray Scattering Studies of Protein Solution Droplets Drying on Micro- and Nanopatterned Superhydrophobic PMMA Surfaces”, Langmuir, 26, 15057-15064 (2010).